Studies to be carried out focus on the question of differentiating actions of testosterone of the mammalian CNS in relation to the process of masculinization and defeminization of mechanisms regulating reproductive function. The subjects of the study are perinatal rats from normal pregnancies and from pregnant rats exposed to a regimen of stress resulting in failure of normal masculinization of sexual behavior in male offsprings. Within this context the following parameters will be studied: Ontogeny of aromatase and of estrogen and adrogen receptors in brain, LH levels in plasma as well as immunoreactive GnRH and LH in the hypothalamus and the anterior pituitary, and the influence of testosterone on nucleic-acids, RNA and DNA, in telencephalic and diencephalic nuclei measured by quantitative cytochemistry.